Darwin's theory of evolution had a profound impact on early functionalist theorists in psychology. Functionalists attempted to objectify mental and behavioral processes in an effort to make psychology more scientific; by focusing on the empirically verifiable external manifestations of internal mental processes, functionalists hoped to make psychology a more exacting science. Functionalists of the Chicago school, following Darwin's focus on the adaptability of organisms, believed that a primary concern of the psychologist should be the adaptive significance of mental and behavioral processes. Psychologists and sociologists alike believed that social order and stability were considered analogous to biological equilibria, as societies, like individual organisms, adapted to their environments.
As Owens & Wagner (1992) point out in the introduction to their Progress in Modern Psychology: The Legacy of American Functionalism, "Even the elusive phenomena of consciousness do not exist in some kind of separate mental world, but rather they evolved to help humans and other organisms adjust to the changing conditions of the natural world. Since psychology is closely allied with biology, it is natural for psychologists to draw evidence from biology" (p. 7). The proponents of functionalism were increasingly concerned not only with immediate (proximate) function, but also with evolutionary (ultimate) function, epigenetic development, and the ecological adaptiveness of each and every behavior class in all species (Dewsbury, D. A., 1989, p. 590). Likewise, sociologists found that phenomena such as social stratification and conflict could be explained using biological metaphors, if not actual fact.
Darwin's theory will be examined as to its effect on behavioral psychology, the best frame of reference by which to judge the impact of his adaptive theory on psychological phenomena. In terms of behaviorism, the emphasis of study should be...